kill off pointless hooks

Any hook implementation that starts off by checking the type of the incoming connection has no business being a hook -- it's the wrong pattern. There's no point the core doing a module_invoke_all() on a connection object if there is only ever one module that has something to say in response. The correct pattern would be a singleton hook (ie the sort where there is a base module), or a magic callback, or indeed now we have objects for connections, a method.

Hooks to kill:

- hook_clients_setparams
- hook_clients_arguments
- hook_clients_fields
- hook_clients_service_options
- hook_clients_connection_save
- hook_clients_call